Variation Among Orchardgrass (Dactylis glomerata) Germplasm for Choke Prevalence Caused by Epichloë typhina

Abstract

Orchardgrass, or cocksfoot (Dactylis glomerata L.), is a cool-season forage grass susceptible to the choke disease caused by Epichloë typhina. Choke has been reported in orchardgrass seed production fields across the temperate regions of the world, but fungicides have not been efficacious in reducing choke incidence or prevalence. To assess the potential for genetic resistance or tolerance of orchardgrass to choke, we evaluated the variation in orchardgrass cultivars and accessions for choke prevalence and characterized infected plants for endophyte secondary metabolite and mating type gene presence. Significant variation was detected across years and locations. Choke prevalence did not always increase with the age of the stand, nor did choke prevalence correlate with flowering time or swathing time of the entries. Both mating types of E. typhina were detected in approximately equal proportions, and no evidence for loline, ergot alkaloid, or indole-diterpene biosynthesis was found. Plants with multiple infected tillers often showed more than one mating type present in the plant, indicating multiple infection events rather than a single infection event that spread to multiple tillers. Both accessions and cultivars with significant choke, and no choke, were detected, which constitute sources of germplasm for further testing and breeding.

Infection Rates and Alkaloid Patterns of Different Grass Species with Systemic Epichloë Endophytes

“…The region encoding the peramine reductase domain has been previously shown to be required for peramine biosynthesis (53). Interestingly, Epichloë typhina in D. glomerata is not known to produce alkaloids (56), which was confirmed recently with D. glomerata infected with Epichloë typhina from Oregon, USA, where the region encoding the perA reductase domain was not detected by PCR (70). We observed variation with the perA markers in our endophyte-infected D. glomerata samples, but since choke in D. glomerata in the USA has only been reported since 1996 (71), genetic variation of E. uncinata in D. glomerata in European grasslands may be greater.…”

Genetic Diversity of the Symbiotic Fungus Epichloë festucae in Naturally Occurring Host Grass Populations

“…lolii ( Hettiarachchige et al, 2015 ). In contrast, mating type gene frequency is found in equilibrium in Epichloë typhina where sexual stage is active ( Bushman et al, 2019 ).…”

Late‐heading parental selection in orchardgrass (Dactylis glomerata L.)

“…woronowii that originated from the former Soviet Union, and cultivar Toyomidori that originated from Central and East Asian sources (Nakayama et al., 2002). All three have been reported to persist and produce forage under abiotic stress and have late HDs (Bushman et al., 2012, 2019; Jensen et al., 2014). Thirty‐three plants from each source were planted in a Latin Square design at the Utah State University Evans Farm, Millville, UT (41°41′52″ N, 111°49′53″ W; 1378 m above sea level; 432 mm annual precipitation; Nibley silty clay loam soil [fi, ne, mixed, mesic, Aquic Argistolls]) in 2015, allowed to open pollinate, and bulk harvested by the three maternal sources.…”

“…woronowii that originated from the former Soviet Union, and cultivar Toyomidori that originated from Central and East Asian sources (Nakayama et al, 2002). All three have been reported to persist and produce forage under abiotic stress and have late HDs (Bushman et al, 2012(Bushman et al, , 2019Jensen et al, 2014 [Fine-silty, mixed, active, mesic Typic Calcixerolls]). Each location had four replications of 94 HS-families arranged in a randomized block design with 10 plants in single row plots for each replication, spaced at 0.5 m within rows and 1 m between rows.…”